Automated brewing machines and other on-demand beverage systems, for brewing beverages such as coffee and tea, usually have a brewing water reservoir in which water is heated by a heating element. The heated water is then transferred from the reservoir to a brewing chamber which holds brewing ingredients such as coffee grounds or tea leaves, through which the heated water flows to produce a brewed beverage. The beverage flows into a container such as a jug or cup located beneath the brewing chamber outlet.
It is commonly known that different flow rates lead to variation of characteristics in the brewed beverage, in particular taste. U.S. Pat. No. 5,901,635 explains that a relatively fast rate of flow of hot water through coffee grounds in the brewing chamber will result in relatively dilute coffee with relatively less flavour and caffeine, than is produced by a slower rate of flow. A relatively slow rate should therefore be used in order to achieve a taste comparable to “regular” or caffeinated coffee which is brewed with a relatively faster rate of flow. The flow rate can be determined by a number of variables, such as the rate at which water is introduced to the reservoir, the size of the conduit or passage between the reservoir and the brewing chamber, and the size of holes in a water distributor or showerhead over the brewing chamber. U.S. Pat. No. 5,901,635 uses an adjustable valve between the filling chamber and the reservoir to adjust the rate of flow of water from the filling chamber to the reservoir.
Many modern domestic beverage machines dispense individual servings of a beverage directly into a drinking receptacle, and derive the beverage from a bulk supply of beverage ingredients or from individual packages of beverage ingredients such as pods, pads or cartridges. In the following specification such packages will be referenced by the general term cartridges. Machines which use such cartridges reduce the need for cleaning and can enable the user to make a selection of beverages such as coffee, tea, hot chocolate and the like. An example of one type of such cartridge is described in EP-A-1440903. The beverages are formed from brewing, mixing, dissolving or suspending the beverage ingredients in water. For example, for coffee beverages, heated water is forced through the cartridges under pressure to extract the aromatic constituents from the compacted coffee grounds contained therein. The use of cartridges in such machines has become increasingly popular due to their convenience and the quality of the beverage produced.
EP-A-1440903 describes a cartridge which is formed from high density polyethylene, polypropylene, polystyrene, polyester, or a laminate of two or more of these materials. The cartridge has an inlet for the introduction of water into the cartridge, and an outlet for a beverage produced from said the beverage ingredients. The cartridge comprises an outer member, an inner member inserted in the outer member and an aperture in a beverage flow path linking the inlet to the outlet for producing a jet of the beverage. The aperture is delimited by an interface between the inner member and the outer member. The cartridge produces a jet of the beverage which can be used to alter the appearance and characteristics of the dispensed beverage, by for example entraining air into the jet of beverage to produce a multitude of small air bubbles in the dispensed beverage.
The afore-mentioned cartridges are designed to be easily assembled with the main components being the inner member and the outer member. By using separate components for the inner and outer members, which are then preferably conjoined on assembly, the manufacture of each component and the assembly of the cartridge can be optimised. This is particularly advantageous where very small tolerances are required for the size and location of the aperture that produces the jet of beverage and also for the remainder of the beverage flow path through the cartridge. However such cartridges utilise a single compaction bed with no means to vary the brew kinetics which can affect the brew efficiency and the flavour, aroma and taste quality of the final product.
WO-02/074661 describes a device for preparing customisable brewed beverages and proposes the use of two ingredient extraction chambers each containing a different volume of ingredients, such as roast and ground coffee. The strength of the finished brewed beverage can be modified by directing the brewing fluid through one or other of the chambers, or dividing the flow to go through each chamber. In another embodiment described in this prior art document, different ingredients are provided in different chambers.
However the use of flow control and diversion valves for the control of the brewing characteristics used in the prior art systems mentioned above adds to the cost and bulk of the machine. The additional moving parts add to the potential for malfunction.
EP-A-1785369 describes a beverage ingredient capsule which is sub-divided into at least two compartments, each containing one or more beverage ingredients. The compartments are constructed such that, when liquid is introduced into the capsule the separate compartments release the contained ingredients at different times so that different beverage components can be produced according to a planned time sequence. One way of achieving this is to separate the compartments with a candy wall, which dissolves when exposed to the liquid.